Why is there even coolant here at all?

[mbouse]

so the original question "Why is there even coolant here at all? " came from another post that began with an intake manifold swap. the original post complained of a coolant leak, and in seeking advice on how to rid the symptom, the forum member asked why there was coolant in the intake manifold.

Mark suggests that the coolant is present to raise the temperature of the air fuel mixture to aid in fuel atomization.

i suggest that the fuel has already been atomized before the mixture hits the intake manifold, and therefore the presence of the coolant is for a different reason; i presume to aid in the warm up phase of early engine run.

i have talked to others who have actually blocked off the coolant ports in their intake manifolds to gain performance of their engines. Additionally, i also present the WELL KNOWN practice of presenting the air breather with as cold of air as possible by any performance seeking modifier.

cold air is denser than warm air, cold air/fuel mixture is therefore MORE air/fuel presented to the combustion chamber and therefore increases performance.

so, here is the invite for discussion: What say you?

[azygoustoyou]

I don't have input on the theory. But I'm here listening.
I would also like to know if it would be best to eliminate the coolant into Valve covers or does it matter.
I have a 32/36 DFEV on an1800 eng.

[BEEK]

in the race motors i built, i blocked off the coolant flow to the intake completly, using a intake gasket from a lancia efi motor. this gasket . port matched the gasket and the manifold. noticed a 5hp improvement immediatly on the chassis dyno.
this gasket is made of the same material as the carb spacers (bakeolite) of however its spelled.

[ventura ace]

Good info is given here:
http://www.rasoenterprises.com/index.ph ... &Itemid=49

Basically, it says that the heated intake manifold will make your street car run better, but if you are racing, then you want the intake to be as cool as possible. Read the whole article to get a better understanding.

Alvon

[kmead]

SNIP

i suggest that the fuel has already been atomized before the mixture hits the intake manifold, and therefore the presence of the coolant is for a different reason; i presume to aid in the warm up phase of early engine run.

SNIP

We have a winner.

The coolant is used to heat the walls of the intake during warmup to reduce condensation of fuel on the walls of the manifold. In addition it keeps the manifold from getting too hot due to heat transfer from the head. The coolant is a mediating feature.

If you look at the performance factory manifold, the waffle for use with twin IDFs, it also has coolant passages for these same reasons.

A cold manifold condenses the fuel out of the mixture making the intake charge lean and later evaporates making it rich as the manifold heats up. The net effect is to minimize surging and lean operation.